Integration of a hot oxygen burner with an auto thermal reformer

ABSTRACT

The present invention relates to integrating a hot oxygen burner with an auto thermal reformer of reducing in a system for generating synthesis gas.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a novel system and process forintegrating a hot oxygen burner with an auto thermal reformer forreducing capital expenditure as compared to existing partial oxidationand autothermal reformer systems. The system also reduces oxygenutilization and soot formation as compared to existing partial oxidationsystem and keeps soot formation to at or below the levels in existingautothermal reformer system. Specifically, the system reduces the sizesof pre-reformer and fired heater or eliminates the need forpre-reformers and/or fired heater entirely. The system further enablesthe use of ‘opportunity fuels’ (as defined below) in the ATR.

Description of Related Art

Hydrocarbons such as natural gas, naphtha, or liquefied petroleum gas(LPG) can be catalytically converted with steam to obtain a synthesisgas (i.e., a mixture of hydrogen (H₂) and carbon monoxide (CO), commonlyreferred to as synthesis gas or syngas. This reforming process could bedone through the use of a so-called steam methane reforming, oralternatively, partial oxidation and auto thermal reforming processes.These generation systems are known, and are typically utilized to obtainsyngas which may be ultimately utilized in the production of hydrogen,methanol, ammonia, or other chemicals. These partial oxidation (“POx”)and auto thermal reforming (“ATR”) systems typically generating syngaswith a low H₂:CO ratio in the range of about 1.5 to 2.5. The ATR systemrequires multiple process steps and pieces of equipment to carry outreforming resulting in capital intensive processes. The POx system, onthe other hand, requires single process step for reforming. However, thePOx system consumes ˜20-30% more oxygen than the ATR system per unitvolume of syngas and it requires more expensive specialized boiler dueto higher temperature of syngas exiting the POx reactor (2500-2700° F.vs. 1800-1900° F. for ATR) and soot formation within the reactor.

For instance, employees of the assignee developed a hot oxygen burnerbased POx technology that drives rapid mixing in the POx reactor using ahot oxygen jet and a patented technique to minimize soot within the POxreactor. This is shown in U.S. Pat. No. 9,540,240. However, HOB-basedPOx systems exhibit the same disadvantages inherent to conventional POxsystems (i.e., high oxygen consumption in comparison to an ATR andhigher capital expenditures in the form of expensive boilers, and thelike.

With reference to FIG. 1, a related art ATR system for generating syngasis shown. Hydrocarbon feedstock stream (1) is mixed with hydrogen (2)and then pre-heated to a temperature ranging from 600-725° F. in heatingcoils (102) and then preheated hydrocarbon stream (5) is fed todesulfurizer (105). Amount of hydrogen mixed with hydrocarbon isgenerally in 2-3% of hydrocarbon feed on a volumetric basis and it isused for aiding reactions within desulfurizer. Desulfurized hydrocarbonstream (8) is mixed with steam (35) and a mixed feed (10) is preheatedto 700 to 950° F. in heating coils (107). The ratio of steam tohydrocarbon (by volume) could vary from 0.4 to 1.5 (i.e., steam/carbonratio). Pre-heated mixed feed (12) is fed to a pre-reformer (110), whereany C₂+ hydrocarbons are reacted with steam so as to convert them intomixture of H₂, CO and CH₄. Pre-reformed feed stream (14) is furtherheated to 1000-1200° F. in heating coils (112) within fired heater (100)and then fed to ATR (120) as pre-heated pre-reformed feed (16). Oxygenneeded in the ATR is produced by air separation unit (“ASU”) (130). Airfeedstock stream (21) is separated into oxygen stream (24) and nitrogen(31) in ASU (130). Oxygen is pre-heated to a temperature ranging from200 to 400° F. in oxygen preheater (135) and preheated oxygen (25) isalso fed to the ATR (120). At the heart of the autothermal reformingprocess is an ATR unit operation (120) that combines a partial oxidation(POx) step and a catalytic reforming step. Within ATR (120), preheatedpre-reformed feed (16) and oxygen (25) react to produce a syngas mixture(20) comprising H₂, CO, CO₂, steam, any unconverted CH₄ and other tracecomponents. Specifically, the feed (16) first reacts with oxygen (25) ina POx step to consume all the oxygen and release heat. The remaininghydrocarbons in the feed are then reformed autothermally (notcatalytically) with CO₂ and H₂O present in the mixture. Since thereforming reactions are endothermic this non-catalytic reforming resultsin a reduction in gas temperature. As the reaction cools, the rates ofreaction (“kinetics”) slow down causing a kinetic limit to theachievable hydrocarbon conversion. To overcome this kinetic constraint,the still hot, reactive, mixture is fed to a catalyst which promotesreforming to achieve a near equilibrium degree of reforming. Due to thenature of the catalyst bed, it is critical that soot not enter thecatalyst as it could cause fouling. Therefore, the conditions in thenon-catalytic zone of the reactor must be maintained to prevent soot atthe entrance to the catalyst. This can be accomplished by preventingsoot from forming in the first place, or by promoting soot gasificationreactions that would consume any soot formed before the gas reaches thecatalyst. For this reason a conventional ATR requires a pre-reformer(110) to convert higher hydrocarbons, which may be prone to sooting inthe POx step, to methane. Further the ATR may use steam injection athigher levels than needed in the catalytic reforming step just to reducesoot formation and enhance soot oxidation.

Syngas (20) exits the ATR at a temperature of 1800-1900° F. and atpressure ranging from 350-550 psia. Syngas (20) is then passed throughprocess gas boiler (150) boiler feed water heater (155) and water heater(160) in sequence to recover thermal energy contained in syngas forsteam generation. Temperature of syngas exiting the process gas boilerranges from 550 to 700° F. Steam is typically generated at 350 to 750psia, however, it can be generated at higher pressure if desired.Finally, syngas is cooled to 80 to 110° F. in a cooler (165) and sent toa condensate separator (170) to separate any condensate. Syngas (32) isthen routed to a downstream process for either making chemicals such asmethanol or Fischer Trope liquids or sent to a purification process forseparating syngas into hydrogen and carbon monoxide. Any residual fuelstream from the downstream process is combined with make-up hydrocarbonfuel stream to form a fuel stream for the fired heater. Burning of fuelin the fired heater provides heat for various heating coils disposedwithin the fired heater. Process water (50) is combined with condensate(52) and heated in water heater (160) to a temperature of 200-210° F.Heated water is fed to deaerator (140) to remove any dissolved gases.Boiler feed water (55) from deaerator (140) is pumped to desiredpressure (generally >450 psia) and heated to temperature that is 10 to50° F. below the boiling point of water and sent to steam drum (125).Hot boiler feed water stream (60) from steam drum (125) is circulatedthrough process gas boiler (150) to generate steam. A portion ofsaturated steam (62) from steam drum is superheated in heating coils(114). The superheated steam (35) is used in the reforming process. Theremainder of saturated steam (70) is exported.

Turning to FIG. 2, a related art partial oxidation process forgenerating syngas is depicted. Hydrocarbon feedstock stream (1) is mixedwith hydrogen (2) and pre-heated to 450-725° F. in hydrocarbon heatingdevice (104) and the preheated hydrocarbon stream (5) is fed todesulfurizer device (105). Desulfurized hydrocarbon stream (8) alongwith oxygen stream (24) from the ASU (130) is fed to the POx reactor(115). Syngas (20) from the POx reactor exits at a temperature of 2500to 2700° F. and at pressure ranging from 350-550 psia. Syngas stream(20) may contain some soot due to cracking of hydrocarbons within thePOx reactor. Due to high temperature and potential presence of soot, aspecialized boiler called syngas cooler (152) is required to cool syngasand generate steam. If steam has no value, syngas cooler can be replacedby quench vessel (not shown) to cool syngas using direct contact withwater. Partially cooled syngas (22) at 550 to 750° F. from syngas cooler(152) is used to preheat hydrocarbon feedstock in the hydrocarbonheating device (104). Syngas stream (23) is then routed and processed ina soot scrubber (154). The soot scrubber includes a venturi scrubber forcontacting syngas with large quantity of water, a contact tower foradditional scrubbing section to remove residual soot from syngas andseparating soot containing water from syngas and pump for circulatingwater. Soot free syngas (26) at 275 to 350° F. is then routed through awater heater (160) and cooler (165) to cool the syngas (30) to 80-110°F. and sent to the condensate separator (170). The syngas product (32)from condensate separator is sent to the downstream process. Processwater (50) is combined with condensate (52) and heated in water heaterdevice (160) to a temperature ranging from 200-210° F. Heated water isfed to deaerator (140) to remove any dissolved gases. Boiler feed water(55) is pumped to desired pressure (generally >450 psia) and sent tosyngas cooler (152) to generate steam. Optionally, boiler feed water canbe heated (not shown) close to its boiling point against partiallycooled syngas prior to feeding it to syngas cooler.

While the partial oxidation system also produces syngas with low H₂:COratio in the range of about 1.5 to 2.5, the oxygen consumption in thePOx reactor is about 25% higher than the ATR system for a comparablequantity of syngas. High grade heat at the exit of the POx reactor iseither used for steam generation or rejected to atmosphere via quenchcooling. Therefore, in order to take advantage of the high temperatures(˜2600° F.) at the exit of the POx reactor, an expensive boiler (i.e.,syngas cooler) is necessary.

In a conventional ATR the burner is designed to rapidly mix the feed(s)and oxygen, often using swirl and other mixing enhancement strategies.These strategies make staging the burner difficult, if not impossible.In other words, in the related art designs all the feed streams arerapidly mixed with the oxygen without the ability to feed differentstreams into different parts of the flame. For instance, in the relatedart U.S. Pat. No. 7,255,840 owned by the assignee of the presentinvention, this rapid mixing was used to mix the hot oxygen-containinggas with the hydrocarbon feed to reduce the mixture temperature belowthe ignition temperature without igniting the mixture, thereby feedingan oxygen and hydrocarbon containing mixture to the catalyst bed.

In contrast, the HOB/ATR reactor of the integrated system of theinvention uses a different mixing strategy. A portion of the fuel isburned in an oxygen stream upstream of a nozzle. The resulting ‘hotoxygen’ stream exits the nozzle and mixes quickly with surroundings.Since the mixing method is that of a simple reacting jet, it is possibleto control how different streams get mixed into the reactive portion. Inthe present invention, the HOB/ATR reactor ignites the oxygen andhydrocarbon containing mixture to perform partial oxidation reactionsprior to the mixture entering the catalyst bed. Therefore, the HOB isdesigned to mix the streams more slowly than that in the related art toensure ignition and avoid soot formation.

To overcome the disadvantages of the related art, such as sootformation, high oxygen consumption and the need for expensive boilers(e.g., syngas coolers), it is an object of the present invention tointegrate an HOB with an ATR reactor in the syngas generation system. Itis another object of the invention, to eliminate the pre-reformer andthe fired heater. By using a catalyst bed to reform a portion of naturalgas by using high grade heat, oxygen consumption per unit volume ofsyngas will be reduced. In addition, exit temperature from such areactor will be below a temperature of ˜2000° F. and will make itpossible to use less expensive process gas boiler. It is yet anotherobject of the invention, to improve the conventional ATR process byreplacing the burner in the ATR by HOB and enable reduction inpre-reformer and fired heater sizes. Further object of the invention isto enable use of unconventional fuels in a conventional ATR process byemploying HOB in the ATR reactor.

Other objects and aspects of the present invention will become apparentto one of ordinary skill in the art upon review of the specification,drawings and claims appended hereto.

SUMMARY OF THE INVENTION

According to an aspect of the invention, unit operation within a systemfor generating syngas is provided. The unit operation includes: a hotoxygen burner assembly integrated with an auto thermal reactor forreceiving a first stream of fuel and oxygen in the hot oxygen burner tocombust said fuel and generate a hot oxygen jet; introducing ahydrocarbon stream in proximity to the exit of the hot oxygen burnerwherein said exit is disposed within the auto thermal reactor; ignitingthe hydrocarbon stream with hot oxygen, performing partial reforming ofthe hydrocarbon in a non-catalytic zone of the auto thermal reactor, andcompleting the reforming in a catalytic reaction zones of the of theauto thermal reactor, thereby forming a syngas which exits the reactorat a temperature below 2000° F. and with minimal soot formation.

In another aspect of the invention, an integrated system for generatingsyngas, including:

providing a hydrocarbon feed stream without pre-reforming and/or heatingsaid hydrocabon feed stream;

splitting said hydrocarbon feed stream between a fuel stream directed tothe hot oxygen burner assembly integrated with an auto thermal reactorand a hydrocarbon feed stream where said fuel stream is combusted withoxygen in the hot oxygen burner assembly of an autothermal reactor toform a hot oxygen jet;

mixing the hydrocarbon feed stream with steam, and introducing saidmixture of hydrocarbon feed in a non-catalytic region of the autothermal reactor wherein the mixture of hydrocarbon feed is substantiallyentrained in the hot oxygen jet; igniting the hydrocarbon stream withhot oxygen to create a reactive jet, thereby performing partialreforming of the hydrocarbon in a non-catalytic zone of the auto thermalreactor; and

further reforming the hydrocarbon in a catalyst bed of the auto thermalreactor to generate syngas.

In yet another aspect of the invention, an integrated system forgenerating syngas is provided, which includes:

providing a main hydrocarbon feed stream without pre-reforming and/orheating said main hydrocarbon feed stream;

splitting the main hydrocarbon feed stream into three fractions, whereinthe first fraction forms a fuel stream, the second fraction forms afirst feed stream, and the third fraction forms a second feed stream;

directing the fuel stream to the hot oxygen burner assembly integratedwith an auto thermal reactor and a hydrocarbon feed stream where saidfuel stream is combusted with oxygen in the hot oxygen burner assemblyof an autothermal reactor to form a hot oxygen jet;

routing the first feed stream to the exit of the hot oxygen burnerwherein said exit is disposed within the auto thermal reactor, whereinthe mixture of hydrocarbon feed is substantially entrained in the hotoxygen jet;

igniting the hydrocarbon stream with hot oxygen to create a reactivejet, performing partial reforming of the hydrocarbon in a non-catalyticzone of the auto thermal reactor,

mixing the second feed stream with steam and routing mixture such thatsecond feed stream mixture is entrained into the reactive jet after thefirst stream is predominantly entrained; and

further reforming the hydrocarbon in a catalyst bed of the auto thermalreactor to generate syngas.

In yet a further aspect of the invention, an integrated system forgenerating syngas is provided. The system includes:

providing a main desulfurized hydrocarbon feed stream split into atleast two hydrocarbon streams wherein a first hydrocarbon stream isrouted to the hot oxygen burner and utilized therein as a fuel which ismixed with oxygen to combust said fuel and generate a hot oxygen jet;

routing the second hydrocarbon stream to a fired heater andpre-reforming the second hydrocarbon stream into a heated pre-reformedhydrocarbon stream;

routing the heated pre-reformed hydrocarbon stream through the firedheater to increase the temperature further, and thereafter introducingthe heated pre-reformed hydrocarbon stream in close proximity to the hotoxygen burner wherein heated pre-reformed hydrocarbon feed issubstantially entrained in the hot oxygen jet to create a reactive jet,thereby performing partial reforming of the hydrocarbon in anon-catalytic zone of the auto thermal reactor; and

completing the reforming in a catalytic reaction zones of the of theauto thermal reactor, thereby forming a syngas.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will be better understoodfrom the following detailed description of the preferred embodimentsthereof in connection with the accompanying figures wherein like numbersdenote same features throughout and wherein:

FIG. 1 is a process flow diagram for a related art ATR reactor basedsystem for generating syngas;

FIG. 2 process flow diagram for a related art POx reactor based systemfor generating syngas; and

FIG. 3 depicts a process flow diagram of the present invention where anHOB is integrated with the ATR based reactor system for generatingsyngas. The system generates syngas without employing pre-reformers andfired heater.

FIG. 3A depicts a sketch of an HOB/ATR reactor used for the processshown in FIG. 3.

FIG. 4 depicts a process flow diagram of another embodiment of thepresent invention where an HOB is integrated with the ATR based reactorsystem for generating syngas. The system generates syngas withoutemploying pre-reformers and fired heater and two hydrocarbon containingstreams are introduced in two different locations of an HOB/ATR reactor.

FIG. 4A depicts a sketch of an HOB/ATR reactor used for the processshown in FIG. 4.

FIG. 5 depicts a process flow diagram of another embodiment of thepresent invention where an HOB is integrated with the ATR based reactorsystem for generating syngas, wherein fuel for HOB bypasses pre-reformerand fired heater.

FIG. 5A depicts a sketch of an HOB/ATR reactor used for the processshown in FIG. 5.

FIG. 6 depicts a process flow diagram of another embodiment of thepresent invention where an HOB is integrated with the ATR based reactorsystem for generating syngas, wherein fuel for HOB and first hydrocarbonfeed bypass pre-reformer and fired heater.

FIG. 6A depicts a sketch of an HOB/ATR reactor used for the processshown in FIG. 6.

FIG. 7 depicts a process flow diagram of another embodiment of thepresent invention where an HOB is integrated with the ATR based reactorsystem for generating syngas, wherein fuel for HOB and first hydrocarbonfeed bypass pre-reformer and fired heater and pre-reformed second feedfor an HOB/ATR reactor bypasses fired heater.

DETAILED DESCRIPTION

The present invention provides for a system and method of integrating anHOB, such as the one developed by the assignee of the current invention,into an ATR reactor to design a syngas generation system that minimizescapital expenditure by either eliminating some of the process units orby reducing the sizing thereof. The “HOB/ATR,” as utilized herein, willbe understood to be a single unit operation, which is at times referredto as a hot oxygen burner assembly integrated with an auto thermalreformer or simply as an HOB-based reactor. The HOB's ability to controlmixing in the ATR reactor such that ignition of the oxygen-containingand hydrocarbon containing streams and subsequent partial oxidationreactions are achieved and soot formation is minimized is leveraged byintegrating it into the ATR reactor. In addition, the system developeddoes not require a pre-reformer and a fired heater, thereby simplifyingthe syngas generation system. The utilization of a catalyst bed toreform a portion of hydrocarbon feed by employing high grade heatresults in a reduction of oxygen consumption per unit volume of syngasgenerated compared to the related art POx system. As utilized herein,hydrocarbon shall be understood to mean a natural gas feed, or arefinery-off gas containing various hydrocarbons as well as hydrogen, COand CO₂ or the like. Further, the exit temperature from an HOB/ATRreactor is below ˜2000° F. and advantageously the syngas generationsystem utilizes a far less expensive process gas boiler.

In the present invention, various streams, process conditions, and unitoperations in common to the exemplary embodiments (and denoted by thesame numerals) will be omitted for the sake of simplicity. In addition,the following terms shall be defined as follows: “total stoichiometricratio” or (“total SR”) shall mean moles of oxygen supplied toprocess/moles of oxygen required to completely combust hydrocarbonssupplied for syngas conversion. It should be noted that in calculationof total SR, only those hydrocarbons that are supplied for syngasconversion are accounted and any hydrocarbons that are used as fuel infired heater are not counted; “burner stoichiometric ratio” or “burnerSR” shall mean moles of oxygen supplied to burner/moles of oxygenrequired to completely combust hydrocarbons supplied to the burner.

Now with reference to FIG. 3, an exemplary embodiment of the inventionwhere the HOB-based ATR system is presented. FIG. 3A shows a sketch ofan HOB/ATR reactor (118) to show non-catalytic and catalytic reactionzones of the reactor and entry locations of various feeds to thereactor. This embodiment has several advantages over the related artdiscussed above. Compared to the system of FIG. 2 wherein the integratedsystem includes either a conventional or an HOB-based partial oxidationunit, the design of process gas boiler is simplified due to lower inlettemperature (˜1900° F. vs. 2600° F.) and minimization of soot in thesyngas. The soot scrubber is not needed due to minimization of sootformation. Compared to the system of FIG. 1 wherein an autothermalreformer is employed, the fired heater and pre-reformer are not neededdue to unique design of burner used in the HOB/ATR reactor thatminimizes soot formation without the use of pre-reforming.

Specifically, in the exemplary embodiment of FIG. 3, hydrocarbonfeedstock stream (1) is pre-heated to 450-725° F. in hydrocarbon heatingdevice (104) and the preheated hydrocarbon stream (5) is routed todesulfurizer device (105) to form hydrocarbon feed stream (8). In thisexemplary embodiment of the invention main hydrocarbon feed stream (8)is split into two separate streams referred to as fuel stream (9) andfeed stream (11). Fuel stream (9), usually amounting to about 5-10% ofmain feed stream (8), is combusted with oxygen (24) by HOB (180) togenerate a reactive hot oxygen jet. The amount of fuel (9) fed to HOB issuch that burner SR value is between 3 and 6. The combustion productfrom HOB is a hot oxygen jet that contains mainly oxygen, CO₂ and H₂O.The feed stream (11) is combined with a steam stream (68) from the steamdrum (125) and the combined mixed feed (15) is introduced in closeproximity to the HOB (180). One way to ensure that mixed feed (15) isintroduced in close proximity to the HOB is by providing an annularsection around HOB as shown in FIG. 3A. Other option is to provide feedports in the HOB/ATR reactor close to where HOB penetrates the reactor(not shown). The amount of oxygen is adjusted such that total SR for thereactor is between 0.28 and 0.33. Thus, oxygen supplied is 0.28 to 0.33times the amount needed for complete combustion of stream 8. Thereaction between hot oxygen jet and combined mixed feed (15) in anon-catalytic zone of the reactor generates syngas. Mixing the streamsin the non-catalytic zone in this manner, the streams (9) and (15) aremixed sufficiently quick to avoid soot formation by the hydrocarbons inthe reactor, but sufficiently slow to avoid soot formation by crackingof the hydrocarbons in the hot gas stream. The syngas than enters thecatalyst bed where further reforming takes place. The syngas (20) exitsthe reactor at about 1800 to 1900° F. and at about 350 to 550 psia. Thesyngas composition depends on relative amounts of hydrocarbon feedstream (8), oxygen (24) and steam stream (68) are supplied in thesystem. Generally, the range of concentrations of various components ona molar basis could be ranging from 40 to 60% for hydrogen, 20 to 35%for CO, 10 to 25% for H₂O, 1 to 7% for CO₂, 0 to 2% of CH₄ and <1% othercomponents including nitrogen, argon, NH₃, and HCN. The lower exittemperature from the reactor (118), enables use of a steam generationsystem comprising process gas reboiler (150) and steam drum (125) thatis similar to that in embodiment of FIG. 1 and significantly lessexpensive compared to more expensive syngas cooler (152) of theembodiment of the related art shown in FIG. 2. In addition, iteliminates the need of pre-reformer (110) or the fired heater (100) ofthe related art embodiments in FIG. 1 or the soot scrubber (154) in therelated art embodiment of FIG. 2, thereby reducing capital expenditure.Partially cooled syngas (22) at 550 to 750° F., from process gas boiler(150) is used to preheat hydrocarbon feed in the hydrocarbon heatingdevice (104). Syngas stream (27) is then routed to a boiler feed waterheater (155) to preheat boiler feed water to about 10 to 50° F. belowits boiling point. Syngas is further cooled through water heater (160)and cooler (165). The cooled syngas (30) is separated in a condensateseparator to generate syngas product (32) for further use in adownstream process.

FIG. 4 depicts an alternative exemplary embodiment, in which mainhydrocarbon feed stream (8) is split into three fractions. One fractionforms first fuel stream (9) with flow ranging from about 5-10% of themain hydrocarbon feed flow of stream (8). Separately, a second fractionforms a first feed stream (11) for reactor with flow of 50 to 85% ofmain hydrocarbon feed stream (8). The third fraction forms a second feedstream (18) with flow of sufficient quantity to achieve the total SRdesired by the operator. This second feed is combined with steam (68) toform a second feed stream (15) for the reactor. First fuel stream (9) isintroduced into the HOB along with oxygen (24) to form a hot oxygenstream and first feed stream (11) is introduced into a section closestto the nozzle of the HOB (180) in reactor (118) such that this firstfeed stream (11) is preferentially entrained into the hot gas jet oversecond feed stream (15). The first feed stream (11) is ignited by thehot oxygen stream to create a reactive jet, partially reforming thehydrocarbon in a non-catalytic zone of the auto thermal reactor. Thesecond feed stream (15) is introduced after first feed stream (11) hasbeen predominantly entrained into the reactive jet. One option forintroducing second feed stream (15) is just upstream of catalyst bed inthe HOB/ATR reactor (118) as shown in FIG. 4A. In this manner, the totalSR value in the non-catalytic reaction zone of the reactor would besimilar to a conventional HOB reactor at 0.35 to 0.37 and syngas exitingthe non-catalytic reaction zone would contain minimal soot. Thus, thesoot is minimized by mixing the streams sufficiently quick to avoid sootformation by hydrocarbons in the reactor, but slow enough to avoid sootformation by cracking of the hydrocarbons in the hot gas stream, asdescribed in detail in U.S. Pat. No. 9,540,240 B2, which is incorporatedherein in its entirety.

The syngas temperature toward the end of the non-catalytic zone (i.e.,in proximity to the non-catalytic and catalytic zone interface) would be2500 to 2700° F. This syngas and second feed stream (18) are mixed justupstream of the catalyst bed and temperature of the syngas decreases tobelow 2100° F. as a result. This syngas then enters the catalyst zone,where thermal energy from the syngas aids in endothermic reforming ofhydrocarbons in the second feed (18). The syngas exiting the reactor(118) is similar in temperature, pressure and composition to thosedescribed earlier for FIG. 3. The total SR value for the entire reactor(non-catalytic and catalytic zones) when all the hydrocarbon containingstream (9), (11) and (18) are considered would be similar to that ofembodiment of FIG. 3 at 0.28 to 0.33.

In the event that steam has no other use in the system, the embodimentsof FIGS. 3 and 4 are envisioned where the system configuration for theembodiments of FIGS. 3 and 4, steam generation equipment process gasboiler (150) and steam drum (125) are replaced by a quench vessel (notshown), which utilizes direct contact with water. Partially cooledsyngas (22) at 550 to 750° F., from process gas boiler (150) is used topreheat hydrocarbon feed in the hydrocarbon heating device (104). Syngasstream (27) is then routed to a boiler feed water heater (155) topreheat boiler feed water to about 10 to 50° F. below its boiling point.Syngas is further cooled through water heater (160) and cooler (165).The cooled syngas (30) is separated in a condensate separator togenerate syngas product (32) for further use in a downstream process.

While FIGS. 3 and 4 shows embodiments with significant simplificationsin systems of prior art, the HOB/ATR reactor can be deployed in aconventional ATR like system of FIG. 1 to achieve improvements over therelated art.

As illustrated in FIG. 5, an alternative exemplary embodiment depicts asystem/process configuration change to that of related art system ofFIG. 1. With reference to FIG. 5A, a sketch of an HOB/ATR reactor (118)including HOB assembly (180) is depicted. Since the ‘fuel’ fed to theHOB (180) is completely combusted before it enters HOB/ATR (118) it ispossible to use non-pre-reformed feed, or opportunity fuels as a fuelstream in HOB. As utilized herein, “opportunity fuels” will beunderstood to mean any hydrocarbon that can provide an economicadvantage, including but not limited to refinery off-gases, tail gases,and other associated gases. As shown in FIG. 5, a portion ofdesulfurized NG (8) is split as a slip stream of hydrocarbon fuel (9),which bypasses pre-reformer (110) and is fed directly to HOB/ATR (118),specifically into HOB assembly (180). This would reduce the need forprereforming this portion of the total feed and associated heating dutywithin fired heater.

In the exemplary embodiment of FIG. 6 a variation in the system of FIG.5 is provided. Starting from the detailed showing of the HOB assembly(180) and the HOB/ATR reactor (118) in FIG. 6A the mixing can becarefully controlled within HOB assembly (180), it is possible tointroduce a specific portion of the feed as first feed stream (19) ahydrocarbon gas split from the hydrocarbon main stream (8) is routednear the burner such that this feed is entrained into the jet prior tointroducing the second feed stream (16) which consists of pre-reformednatural gas. Since reactions in this portion of the jet are fuel leanenough to avoid soot formation, it can be possible to feed unreformedfeed into this region without forming soot. The remaining feed can thenbe mixed into the later part of the jet, after the first feed stream(19) is predominantly entrained in the jet, and take the mixture down tothe final stoichiometric ratio. Specifically, with reference to FIG. 6,in this embodiment, desulfurized hydrocarbon main stream (8) is splitinto three fractions: hydrocarbon fuel stream (9) which is fed toHOB/ATR (118) to support the fuel lean combustion, specifically into HOBassembly (180); stream of hydrocarbon (19) which is fed as first feed toHOB/ATR (118), specifically into close proximity of HOB assembly (180)and a stream of desulfurized hydrocarbon (18), which is first routedthrough fired heater (100). Desulfurized hydrocarbon feedstock stream(18) is mixed with steam stream (35) and processed through pre-reformer(110) and fired heater (100) as described with respect to the embodimentof FIG. 1 to generate pre-heated pre-reformed feed stream (16), which isfed to HOB/ATR (118) as second feed stream. In this embodiment thereaction of the hydrocarbon fuel stream (9) and the fuel lean combustionproduct from the HOB assembly (180) are not likely to form soot.Therefore, the pre-reformer duty can be reduced, and in some situationsalternative fuels from within or outside the integrated system could beused, in essence reducing the size of the fired heater and/or thepre-reformer and enabling use of lower cost fuel and/or refinery off-gasstreams.

In yet another exemplary embodiment and with reference to FIG. 7 in thisconfiguration it is not necessary to preheat pre-reformed feed (14)prior to feeding it to HOB/ATR (118). Therefore, in this embodiment,pre-reformed hydrocarbon feed (14) is directly fed to HOB/ATR (118) asecond feed. Thus, eliminating the preheating of this steam reduces theduty of the fired heater. In addition, the total SR is increased,thereby reducing the soot forming potential.

The invention is further explained through the following examples, whichcompare the related art embodiments with the various ones of the presentinvention, and those based on various embodiments of the invention,which are not to be construed as limiting the present invention.

EXAMPLES

Process simulations were carried out for various embodiments describedabove. Main feed and product streams conditions used in all simulationsare listed in Table 1. Natural gas was used as a hydrocarbon feed in allthe simulations. All the embodiments were compared for a fixed flow of20 MMscfd for H₂+CO content in syngas product (32). Amounts of feed andproduct streams per unit volume of syngas varied between variousembodiments as indicated in Table 2. Also, syngas compositions weresomewhat different for different embodiments as indicated by H2/COratios in Table 2.

TABLE 1 HC feed Oxygen Syngas Export steam (1) (24) (32) (65)Temperature [F.] 70.0 100.0 100.0 505.7 Pressure [psia] 613.5 585.0461.5 716.7 Mole Fractions Methane 0.905900 Ethane 0.036100 Propane0.007800 i-Butane 0.003100 n-Butane 0.004500 Nitrogen 0.012595 CO20.030000 H2S = mercaptans 0.000005 Oxygen 0.996 Argon 0.004 H2O 1.000

Table 2 summarizes key comparative parameters of syngas generationsystems in the embodiments of FIGS. 1 through 7, detailed above. All theembodiments of this invention (FIGS. 3 through 7) achieves H2/CO ratioof between 2.2 to 2.4. Embodiments of FIGS. 3 and 4 consume about thesame NG while consuming ˜10% less oxygen in comparison to relate artembodiment of FIG. 2. This improved performance is achieved byembodiments of FIGS. 3 and 4 while simultaneously reducing processcomplexity by eliminating soot scrubber and using a lower cost boilerwhen compared to FIG. 2. When compared to the related art embodiments ofFIG. 1, the embodiments described with respect to FIGS. 3 and 4 consumeslightly less NG and ˜22% more oxygen while significantly loweringprocess complexity by eliminating fired heater and pre-reformer.

TABLE 2 FIG. 1 FIG. 2 (related (related Emodiment art) art) FIG. 3 FIG.4 FIG. 5 FIG. 6 FIG. 7 H2 + CO in SG, 20 20 20 20 20 20 20 MMscfdNG/(H2 + CO) 0.388 0.380 0.377 0.382 0.391 0.396 0.395 O2/(H2 + CO)0.200 0.272 0.245 0.246 0.204 0.209 0.226 H2/CO ratio 2.4 1.6 2.2 2.22.4 2.4 2.4 Steam export, 27584 44281 30668 31068 29921 29738 29589lb/hr Prereformer size 1 n/a n/a n/a 0.95 0.68 0.68 Fired heater size 1n/a n/a n/a 0.98 0.89 0.56 Steam generation PGB SG PGB PGB PGB PGB PGBequipment cooler Soot scrubber No Yes No No No No No required?

Embodiments of FIGS. 5, 6 and 7 consumes slightly more NG and oxygencompared to the related art embodiment of FIG. 1 while achieving sizereduction for the fired heater between 5% and 32% and that for thepre-reformer between 2% and 44%.

While the invention has been described in detail with reference tospecific embodiments thereof, it will become apparent to one skilled inthe art that various changes and modifications can be made, andequivalents employed, without departing from the scope of the appendedclaims.

What is claimed is:
 1. A unit operation within a system for generatingsyngas, comprising: a hot oxygen burner assembly integrated with an autothermal reactor for receiving a first stream of fuel and oxygen in thehot oxygen burner to combust said fuel and generate a hot oxygen jet;introducing a hydrocarbon stream in proximity to the exit of the hotoxygen burner wherein said exit is disposed within the auto thermalreactor; igniting the hydrocarbon stream with hot oxygen, performingpartial reforming of the hydrocarbon in a non-catalytic zone of the autothermal reactor, and completing the reforming in a catalytic reactionzones of the of the auto thermal reactor, thereby forming a syngas whichexits the reactor at a temperature below 2000° F. and with minimal sootformation.
 2. The unit operation of claim 1, wherein the first stream offuel is an opportunity fuel.
 3. The unit operation of claim 1, furthercomprising: introducing a second stream of hydrocarbon upstream of thecatalytic reaction zone in the reactor.
 4. An integrated system forgenerating syngas, comprising: providing a hydrocarbon feed streamwithout pre-reforming and/or heating said hydrocarbon feed stream;splitting said hydrocarbon feed stream between a fuel stream directed tothe hot oxygen burner assembly integrated with an auto thermal reactorand a hydrocarbon feed stream where said fuel stream is combusted withoxygen in the hot oxygen burner assembly of an autothermal reactor toform a hot oxygen jet; mixing the hydrocarbon feed stream with steam,and introducing said mixture of hydrocarbon feed in a non-catalyticregion of the auto thermal reactor wherein the mixture of hydrocarbonfeed is substantially entrained in the hot oxygen jet; igniting thehydrocarbon stream with hot oxygen to create a reactive jet, therebyperforming partial reforming of the hydrocarbon in a non-catalytic zoneof the auto thermal reactor; and further reforming the hydrocarbon in acatalyst bed of the auto thermal reactor to generate syngas.
 5. Theintegrated system of claim 4, wherein the fuel stream is an opportunityfuel.
 6. The integrated system of claim 4, wherein the syngas exitingthe auto thermal reactor at a temperature below 2000° F. and at 350 to550 psia.
 7. The integrated system of claim 4, wherein the fuel streamis about 5-10% by volume of the hydrocarbon feed stream.
 8. Theintegrated system of claim 4, wherein the syngas generated is routed toa process gas reboiler and further downstream unit operations.
 9. Anintegrated system for generating syngas, comprising: providing a mainhydrocarbon feed stream without pre-reforming and/or heating said mainhydrocarbon feed stream; splitting the main hydrocarbon feed stream intothree fractions, wherein the first fraction forms a fuel stream, thesecond fraction forms a first feed stream, and the third fraction formsa second feed stream; directing the fuel stream to the hot oxygen burnerassembly integrated with an auto thermal reactor and a hydrocarbon feedstream where said fuel stream is combusted with oxygen in the hot oxygenburner assembly of an autothermal reactor to form a hot oxygen jet;routing the first feed stream to the exit of the hot oxygen burnerwherein said exit is disposed within the auto thermal reactor, whereinthe mixture of hydrocarbon feed is substantially entrained in the hotoxygen jet; igniting the hydrocarbon stream with hot oxygen to create areactive jet, performing partial reforming of the hydrocarbon in anon-catalytic zone of the auto thermal reactor, mixing the second feedstream with steam and routing mixture such that second feed streammixture is entrained into the reactive jet after the first stream ispredominantly entrained; and further reforming the hydrocarbon in acatalyst bed of the auto thermal reactor to generate syngas.
 10. Theintegrated system of claim 9, wherein the fuel stream is an opportunityfuel.
 11. The integrated system of claim 9, wherein the fuel stream isabout 5-10%, the first feed stream is about 50-85% and the second feedstream is about 10-45% by volume of the main hydrocarbon feed stream,respectively.
 12. An integrated system for generating syngas,comprising: (a) providing a main desulfurized hydrocarbon feed streamsplit into at least two hydrocarbon streams wherein a first hydrocarbonstream is routed to the hot oxygen burner and utilized therein as a fuelwhich is mixed with oxygen to combust said fuel and generate a hotoxygen jet; (b) routing the second hydrocarbon stream to a fired heaterand pre-reforming the second hydrocarbon stream into a heatedpre-reformed hydrocarbon stream; (c) routing the heated pre-reformedhydrocarbon stream through the fired heater to increase the temperaturefurther, and thereafter introducing the heated pre-reformed hydrocarbonstream in close proximity to the hot oxygen burner wherein heatedpre-reformed hydrocarbon feed is substantially entrained in the hotoxygen jet to create a reactive jet, thereby performing partialreforming of the hydrocarbon in a non-catalytic zone of the auto thermalreactor; and (d) completing the reforming in a catalytic reaction zonesof the of the auto thermal reactor, thereby forming a syngas.
 13. Theintegrated system of claim 12, wherein the first hydrocarbon feed streamis an opportunity fuel.
 14. The integrated system of claim 12, furthercomprising: splitting a third hydrocarbon stream from the desulfurizedhydrocarbon feed stream and introducing said third hydrocarbon stream inclose proximity to the hot oxygen burner disposed in the auto thermalreformer and introducing said heated pre-reformed hydrocarbon feed, suchthat the heated pre-reformed hydrocarbon feed is entrained into thereactive jet after the second hydrocarbon stream is predominantlyentrained.
 15. The integrated system of claim 1, the first and thirdhydrocarbon streams are low cost opportunity fuels.
 16. The integratedsystem of claim 10, wherein the heated pre-reformed hydrocarbon streamof step (b) is introduced directly in close proximity the hot oxygenburner thereby performing partial reforming of the hydrocarbon throughpartial oxidation reactions in the non-catalytic zone of the autothermal reactor.